Field of the Invention
The present invention relates to a plastic cap assembly for a container with a neck that is sealed by foil or a membrane, this having a base cap with a pour spout and a penetrator, as well as a cap or a cover with a seal that covers the pour spout in the base cap.
Cap assemblies of this kind are already known from U.S. Pat. Nos. 4,456,150 and 4,696,408. These cap assemblies have safety devices that keep the base cap or the cap or cover, respectively, in an upper safety position relative to the upper edge of the container neck and which can only be moved into a lower position after removal of the safety device, in which connection, during this relative movement towards the container neck, parts of this cut or penetrate the sealing membrane or foil with appropriate means that are provided for this purpose.
Even though cap assemblies of this kind have proved themselves in use from a purely technical standpoint, one unanticipated problem has arisen. Although removal of the safety seal can be managed correctly by the majority of end users, experience has shown that this does not apply to the second step involved in opening the cap assembly. The cap assembly must now be moved into a lower position that orients it towards the container neck in order to penetrate the foil or membrane. For the end user, this corresponds to a closing-type movement. However, since the user wants the container opened, he does not complete the functionally correct but seemingly illogical movement, but rather attempts to open the cap completely by a corresponding turning movement or by pulling on it. If he succeeds in so doing, he then finds the still intact foil or membrane, whereupon he penetrates this and then screws the cap assembly back in place. This in no way corresponds to the correct procedure. Some cap assemblies are fitted with safety seals so that the cap cannot be pulled off or screwed off. Unfortunately, it has been found that this has only led to the fact that end users who have not understood the proper procedure for opening the cap assembly have used so much force that the cap assembly has been destroyed.
A second, purely technical, problem with such cap assemblies with an upper sealed position and a lower use position lies in the fact that the foil or membrane that seals the neck of the container is not supported by the cap assembly when in the sealed position. This renders the guarantee of such sealing questionable. Under some conditions, the pressure beneath the membrane or foil can fluctuate. If the cap assembly is not on the foil or membrane that is applied to the neck of the container, the foil or membrane can only be welded onto the container neck through the cap assembly either inadequately or not at all by induction welding. Leakage is then unavoidable in the event that there is even a slight increase in pressure beneath the membrane.
Examples of the most frequent causes of such pressure increases are improper transportation (upside down), the generation of gases during fermentation processes, temperature increases, or shaking.